i have a 2008 dodge ram 3500 with the 6.7l cummins. every few years it seems like the battery need to be replaced. well this time came along and replaced the batteries. also replaced the alternator with a higher charging wattage too. cleaned the battery terminals and spray a protector on the terminals. at first this helped until it started “laboring” to turn over. seems like it doesn’t have enough juice to turn it over. i measured battery voltage with key off and it was 12.41. turn the key on and i went down to 12.09. i didn’t measure cranking just yet. i don’t know if those are good enough voltages. now it’s clicking behind the dash and the guages don’t immediately start working. no clue what this is. took my obd2 scanner out and had stored codes- P-2509 and P0562. super confusing. need help
heres the link to the video i uploaded of starting it
https://youtu.be/mU7Y_YgBwGk

 

Need to have a look at the power feeds to the PCM. Of course, that assumes that the battery is charged up, and the charging system is working.....

 

okay so i cleared those codes and they haven’t came back. however it’s super weak turning over and it’s still clicking from behind the gauge cluster. the terminals are cleaned but are kinda screwed. New terminals? New starter? just don’t know where to go from here

 

Take it to your local parts store, have the charging system, and battery tested, along with a starter draw test. See what shakes loose. Bad connections at the battery will cause this, as will other things as well.

 

Maybe some earthing problem somewhere?

 

hooked my multimeter and started it and battery voltage dropped down to 8 volts. i’m not sure but that seems pretty low. but then hops up to 14 charging.

 

If it dropped to 8v when cranking your battery is toast. Surprised it started.

 

replaced both batteries less than a month ago

 

Just because its 'new', doesn't necessarily imply that it is 'good'. Put a full charge on the batteries. Test again. If you still have voltage dropping that low, then one, or both, batteries are bad.